Conventional arrangements of transceiver circuitry in a wireless cellular system base station or other similar communication system application typically include receiver and transmitter devices implemented at least in part using radio frequency (RF) components that are discrete rather than integrated. Such devices are typically located remotely from the corresponding antenna circuitry, and coupled thereto via coaxial cable or other similar connection mechanism. For example, a single base station transmitter including one or more power amplifiers may be coupled via coax to antenna circuitry comprising multiple antenna elements. Each of the multiple antenna elements may be associated with a different directional antenna or antenna sector of the base station. The receiver is configured in a similar manner, and generally processes signals received via the same set of antenna elements used for transmission. The transmitter and receiver thus share a common set of antenna elements. A diplexer filter is typically arranged between the antenna elements and the transceiver circuitry in order to separate transmit signals from receive signals.
FIG. 1 shows an exemplary base station 100 configured in the conventional manner described above. The base station 100 includes baseband circuitry 102 which is coupled to a transmitter 104 and to a receiver 106, each implemented at least in part utilizing discrete RF components. The transmitter 104 and receiver 106 are coupled via coaxial cable connections 108 to a set 110 of antenna elements 112. The coaxial cable connections 108 also typically have associated therewith a plurality of power splitters for dividing a given transmit signal equally among the multiple antenna elements. Similarly, signal combiners may be used to combine receive signals from the multiple antenna elements.
The typical conventional arrangement of base station transceiver and antenna circuitry as illustrated in FIG. 1 has a number of significant drawbacks.
One such drawback is that the discrete RF components are generally bulky and expensive, and therefore increase the size, cost and power consumption of the base station. Moreover, such components, particularly power amplifiers, are unduly susceptible to failure.
Power amplifiers are typically the most expensive RF components in the base station transceiver circuitry. Although it is known that integrated circuit transistors generally provide higher operating frequencies than standard discrete power amplifier transistors at lower cost, integrated circuit transistors generally allow only limited voltage swings and provide poor impedance match into standard off-chip circuitry. The discrete power amplifier transistors therefore continue to be used in the conventional arrangements.
Another drawback associated with the use of discrete RF components in the base station transceiver circuitry is that configuration flexibility is unduly limited. Generally, a particular transmitter or receiver design based on discrete RF components is not readily reconfigurable to accommodate changes in system requirements or communication standards. For example, power amplifiers are generally specifically designed and optimized for operation over a relatively narrow bandwidth, although a broadband design capable of reconfiguration to support different system configurations and multiple standards would be preferable.
Yet another problem is that the coaxial cable connections 108 and their associated power splitters and combiners are generally expensive as well as lossy, thereby contributing to the inefficiency of the conventional arrangement.
Furthermore, the above-noted diplexer filter is also typically a bulky and expensive item, contributing significantly to the size and cost of the base station transceiver circuitry.
In view of the foregoing, it is apparent that a need exists for improved techniques for implementing transceiver and antenna circuitry in a wireless system base station or other communication system application.